Filter systems used in swimming pools, spas, hot tubs and whirlpools often rely on particulate filters, such as sand beds, to trap and remove particulate contaminants from the water and chlorine of sufficient concentration in the water to kill harmful bacteria, algae and fungus which may inhabit the water.
Such systems suffer several disadvantages. For example, the particulate filter must be periodically back-flushed to clear it of accumulated debris, often requiring that the filter system be taken down for a period of time during the back-flushing. The most objectionable disadvantage is the use of chlorine to kill harmful bacteria in the water, however. Chlorine in the water causes a strong chlorine odor to permeate the area around the pool or spa. This odor becomes especially objectionable when the spa or pool is located indoors, because the odor becomes concentrated and the area must be ventilated to keep the chlorine odors down. Chlorine furthermore attacks certain plastics and fibers, causing deterioration and bleaching of pool or spa accessories, as well as swimming or spa apparel. Users of the pool or spa must shower or bathe to rid themselves of the chlorine odor after each use of the pool or spa.
There is clearly a need for filters and a filter system that substantially reduces or even eliminates entirely the use of chlorine to maintain safe, filtered water, free of harmful bacteria in spas or pools and which does not require extensive maintenance, such as back-flushing.